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Efficacy of oral administration of cystine and theanine in patients with colorectal cancer undergoing capecitabine-based adjuvant chemotherapy after surgery: study protocol for a multi-institutional, randomised, double-blinded, placebo-controlled, phase II trial
  1. Reo Hamaguchi1,
  2. Takashi Tsuchiya2,
  3. Go Miyata3,
  4. Toshihiko Sato4,
  5. Kenichi Takahashi5,
  6. Keisuke Ariyoshi1,6,
  7. Shunsuke Oyamada6,
  8. Satoru Iwase1
  1. 1 Department of Palliative Medicine, The Institute of Medical Science, The University of Tokyo, Tokyo, Japan
  2. 2 Department of Gastroenterological Surgery, Sendai City Medical Center Sendai Open Hospital, Sendai, Japan
  3. 3 Department of Gastroenterological Surgery, Iwate Prefectural Central Hospital, Iwate, Japan
  4. 4 Department of Surgery, Yamagata Prefectural Central Hospital, Yamagata, Japan
  5. 5 Department of Colorectal Surgery, Tohoku Rosai Hospital, Sendai, Japan
  6. 6 Japanese Organisation for Research and Treatment of Cancer (JORTC), NPO, Tokyo, Japan
  1. Correspondence to Dr Reo Hamaguchi; reo-h{at}


Introduction Although adjuvant capecitabine therapy for patients with colorectal cancer after surgery often causes adverse events (AEs), such as diarrhoea, stomatitis, anorexia and hand-foot syndrome (HFS), there are no standard prevention therapies. Cystine and theanine were reported to attenuate some chemotherapy-associated AEs, and are also expected to attenuate the AEs caused by capecitabine treatment. Therefore, our present study aimed to determine the safety and efficacy of cystine/theanine therapy in patients with colorectal cancer undergoing capecitabine-based adjuvant chemotherapy after surgery.

Methods and analysis A multi-institutional, prospective, randomised, double-blinded, placebo-controlled, phase II trial is being planned. Patients with colorectal cancer treated with capecitabine as an adjuvant chemotherapy will be randomised into either the cystine/theanine group (n=50) or placebo group (n=50). Data will be collected during four courses of capecitabine therapy. The primary endpoint will be incidence rate of diarrhoea of grade 1 or higher in accordance with the Common Terminology Criteria for AEs (CTCAE) v.4.0, Japanese Clinical Oncology Group (JCOG) version. The secondary endpoints are incidence rates of other AEs (CTCAE v.4.0-JCOG), scores of the Japanese version of the European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire module for all patients with cancer (QLQ-C30) and for patients with colorectal cancer (QLQ-CR29), incidence rate of HFS according to the HFS grading scale, protocol adherence, completion rate of four courses of capecitabine therapy and the proportion of completion without delay or dose reduction, time to completion of four courses of capecitabine and total dose of capecitabine. A sample size of 100 patients will be analysed between November 2016 and April 2018.

Ethics and dissemination Ethical approval was obtained at all participating institutions. The results of this study will be submitted for publication in international peer-reviewed journals.

Trial registration number UMIN000024784; Pre-results.

  • cystine and theanine
  • capecitabine
  • colorectal cancer
  • adjuvant chemotherapy
  • adverse events
  • hand-foot syndrome

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  • Contributors RH, TT, GM, TS, KT, KA, SO and SI participated in the design of the study. SO performed the statistical analysis. All authors contributed to writing and critically revising the manuscript, and all gave their final approval of the version to be published.

  • Funding This trial was supported by Ajinomoto Co., Inc.

  • Disclaimer The company did not have any role in the study design, data collection, management, analysis or interpretation of the data, writing of the manuscript or the decision to submit the manuscript for publication.

  • Competing interests None declared.

  • Patient consent Obtained.

  • Ethics approval Japanese Organisation for Research and Treatment of Cancer Protocol Review Committee and the Institutional Review Board at each participating institution (Sendai Open Hospital, Iwate Prefectural Central Hospital, Yamagata Prefectural Central Hospital, and Tohoku Rosai Hospital).

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Author note The JORTC Data Center and JORTC Independent Data Monitoring Committee have access to the final trial dataset. There is no contractual agreement regarding the investigators’ access restrictions to the dataset.

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